McGeorge Bundy's father had been an assistant to Secretary of War Henry L. Stimson, and at Yale the younger Bundy wrote a highly-praised essay arguing against an isolationist foreign policy. After military service in World War II he became an assistant to Naval Admiral Alan G. Kirk. He later worked for Stimson, co-authoring his autobiography and ghostwriting Stimson's 1947 article for Harper's, "The Decision to Use the Atomic Bomb", which first put forth what became the standard response to criticism of Harry S. Truman's use of atomic weapons, that a conventional invasion of Japan could have cost a million American lives. In the late 1940s he served on the Economic Cooperation Administration, which administered the Marshall Plan, and with books and frequent opinion columns during his academic and administrative career at Harvard, Bundy came to be seen as an expert on foreign affairs.

Appointed National Security Advisor by President-elect John F. Kennedy in 1960, he offered a fountainhead of bad advice, recommending the disastrous Bay of Pigs operation against Cuba, arguing for a surgical strike at Soviet missile silos during the Cuban missile crisis, and urging an increased American military presence in Vietnam. After Kennedy's death Bundy remained as National Security Advisor to Lyndon B. Johnson, endorsing further military involvement in Vietnam. For the rest of his life he was seen as a somewhat controversial figure for his support of that war, and when he joined the faculty of New York University, two dozen professors resigned in protest. When a reporter once asked if he had any regrets about his advice on Vietnam, Bundy famously replied, "Yes, but I'm not going to waste the rest of my life feeling guilty about it".

Author of books:On Active Service in Peace and War (1948, memoir)The Strength of Government (1968, politics)Presidential Promises and Performance (1980, politics)Danger and Survival: Choices about the Bomb in the First Fifty Years (1988, international affairs)Reducing Nuclear Danger: The Road Away from the Brink (1993, international affairs)